Electric-elevator-control system



S. W. RUSHMOBE.

ELECTRIC ELEVATOR CONTROL SYSTEM. APPLICATION FILED NOV. 7, 1919.

1 427 44 Patented Aug. 29, 1922.

2 SHEETS$HEET I. c9129. 1

nwmron TORI/EV s ars U N l T SAMUEL "W. RUSHMORE, OF PLAINFIELD, NEWJERSEY.

FEJQEQZTRIG"EEIJEVATOR-CdNTROL SYSTEM.

Specification of Letters Patent. Patented Aug, 29, 1922,

Application filed November 7, 1919. Serial No. 336,348.

To all whom it may concern:

Be it known that I, SAMUEL W. BUSH- MORE, a citizen of the UnitedStates, and resident of Plainfield, in the county of Unlon and State ofNew Jersey, have invented certain new and useful ImprovementsinElectric-Elevator-Control Systems, of which the following is aspecification.

' its objects to provide a system of this type This invention relatesmore particularly to elevator systems for control of a plurality or abank of elevators, and has as one of in whlch the apparatus shall berelatively simple and inexpensive to manufacture and at the same time,reliable, safe and economical in'operation. v

In its preferred embodiment, the invention particularly concerns thattype of elevator control system in which a separately excited elevatormotor derives its current from a separately excited generator and inwhich control is effected without the interposition of seriesresistances or similar power wasting devices.

A feature of the preferred form of the invention is the use of a singlegenerator of a special known design for supplying at one time anycombination of or all of a plurality of elevator motors, the motorsbeing associated with the generator in such manner, that each motor maybe operated for delicate control of start and stop as well as speed anddirection of movement of the corresponding elevator, independently ofall of the other motors and their corresponding elevators. My system,while utilizing buta single generator for operating a plurality ofelevators, nevertheless secures the same reliability and flexibility ofservice as if a separate generator supplied each motor while at the sametime effecting a considerable increase in efficiency of operation,decrease in first cost and decrease in space required.

Another feature of the invention is an arrangement whereby the elevatorsare allowed to effect their downward travel by gravity, and the energygenerated in descent'isused to operate the corresponding motor as agenerator for returning energy to the source of power. A preferredarrangement for bringing about this result is to provide a manualcontrol for each elevator disposing the same in such manner that whenset for downward travel of the elevator the, connections between thecorresponding motor and the generator become reversed,

whereby the motor will generate current and supply it to the generatorin the proper direction for aiding the prime mover. This reversal ofconnections between the generator and the motors is preferably effectedin such manner as to avoid destructive sparking and preferably this isaccomplished by means for effecting an automatic cessation ofthe'current deliveredto the motor immediately. prior to reversing thecircuit connections.

The above and other features of my invention will be more fullyunderstood from the following detailed description in connection withthe accompanying drawings in Figure 1 is a diagrammatic view of oneembodiment of my invention; and

tion.

In these drawings the numeral 1 designates a generator havinga fieldframe 2 and preferably equally spaced 90 degrees from each other, Thearmature is provided with four brushes 7, 8, 9 and 10, said brushesbeing preferably equidistantly spaced 90 degrees .apart, each brushbeing disposed half way between adjoining field poles.

The generator 1 is separately excited from a pair of mains 11 and 12.For this purpose two parallel field circuits 34 and 35 branch from alead 33 connected to the main 12, each said field circuit correspondingto one of the field sections, the field circuits being completed to themain 11 in a manner explained below.

In the type of generator just described, current may be delivered to oneexternal circuit through the brushes 7 and 10 and to another separateand independent circuit, through the brushes8 and 9. It will be seen byreference to my Patent No. 587 ,163, granted July 27th, 1897, in whichthis type of generator is described, that the same has the property ofmaintaining the different ex- Figure 2 is a similar view of amodificaternal circuits which it may supply, subtor shown on thedrawings has but two magnetic field sections, comprising four poles andfour brushes as above described, said gcncrator supplying the currentfor operating two elevators as will be described more fully below. It iswell known, however, that generators of the type described may be builtwith any number of pairs of poles within the limits of practical use andthat consequently any number of elevators may derive their operatingcurrent from a single generator of the type referred to, the latterhaving a pair of poles and a pair of brushes for each elcvator.

The type of generator shown and described will be designated by me amultivoltage generator and each individual segment or portion of thegenerator that supplies one of the independent external circuits, willbe designated a generator section.

Referring again to the drawings, 1 have shown two separate elevatormotor circuits A and B, the circuit A being fed from the brushes 7 and10 and the circuit B from the brushes 8 and 9. As the two circuits A andB have the same elements identically arranged, the detailed descriptionwill be confined to circuit A, it being understood that it also appliesto circuit B or to any additional elevator motor circuits where amultivoltage generator of a number of poles greater than shown in thedrawings is employed.

The elevator motor is conventionally shown with an armature 13 and fieldpoles 14 separately excited from the mains 11-12 through leads 15-16.The generator brush 7 is connected by a lead 17 to the central contact18 of a motor reversing switch 19, andfrom the generator brush 10, alead 20 is connected to the right hand contact 21 of the reversingswitch and a spur 22 from said lead being connected to the left handreversing switch contact 23. The movable reversin switch as shown hastwo preferably parallel blades 25 and 26 mounted upon an insulatingsupport 27 pivoted as at 24-. Leads 28 and 29 respectively connect themain brushes of the motor 13 to the blades 25 and 26. As shown in thedrawings blade 25 engages contact 23 and blade 26, contact 18. Currentwill therefore be supplied froin the generator to the elevator motor,and when the reversing switch is moved to the right into contact withlimiting stop 32, it will reverse the connections between the generatorand the motor.

For effecting the control of the elevator, I provide preferably amanually operated controller C in the elevator car (not shown). Thiscontroller comprises a pivoted arm 36 cooperating with two sets ofsymmetrically disposed contacts 37 and 37'. By way of example the setcomprises three contacts 39,

1 name y;

41) and 11, a rcsistancc -12 connecting contacts 39 and h) and aresistance 13 connect:- ing contacts 10 and +1. The correspondingcontacts on the right hand side of the concontroller arm and a lead 4:6to lead 16 and hence to the main 11, thus completing the generator fieldcircuit.

The reversing switch 13) is magnetically operated from the mains 11-12,the controller C governing such operation. To this purpose there arepreferably a pair of electro-Inagnetic coils 17 and 18 on opposite sidesof the reversing switch 19, said coils having a common core 19 connectedto the end of the insulating switch support 27. Both electro-magneticcoils 17 and 48 are connected at one end as shown at 50 and .51respectively to the lead 15. The other end of the coil 417 is connectedby a lead 52 to the control contact 11 and the second terminal of coils18 is connected by a lead 53 to the control contact 11. Theelectro-Inagnctic coils -17 for operating the reversing switch thusderives its current from the mains 11 and 12, the circuit being from themain 12 through lead 15 tolead 50 to coil 17 and from the coil throughlead 52 to contact 41 and when control arm 36 is in any position to theleft of neutral the current passes through said arm to lead 46, thenceto lead 16 and back to the main 11. The circuit for coil e8 is similarto that for coil 17, it being necessary to move the arm 36 to therightof neutral for energizing the coil.

When the controlarm '36 is in the central or neutral position, it iselectrically separated from all of the controller'contacts. Accordinglythe field circuit corresponding to the section A of the generator isbroken, and the coils 47 and 18 of the reversing switch are notenergized. The field 14 of the motor, however, is fully excited from themains 11 and 12, through the leads 15 and 16.

The elevator is preferably provided with automatic electric brakes (notshown) on the hoist drum (not shown). Should this brake fail, and thecar starts moving by gravity either downward by excess loader upward byexcess of counterweight, it will drive the motor 13, and by reason ofthe fact that at this time the armature is short circuited through thelow resistance generator armature and the field poles are excited, alarge and effective dynamic braking current will be generated. The shortcircuit current in the armature will become so heavy I even. at slowrotation that the car could move by. gravity at only a creeping paceshould the brake fail. My system thus acts as an uxiliary safety devicefor preventing unrestrained falling of the car,

In normal operation when the car is to ascend, the operator moves thecontroller arm 36 in the appropriate direction. Assumingthis directionto be't'oward the left in the specific embodiment shown, the firstcontact-reached by the arm will be contact 41. At this time the fullvoltage of the supply mains 11 and 12 will be applied across theterminals of the electro-magnetic coil 47, the

circuit being from main 12through lead 15, lead 50, electro-magneticcoil 47, lead 52, contact 41, arm 36, lead 46 and lead 16, back to themain 11. The electro-magnetic coil 48 remains unexcited. Accordingly thecore 49 will be sucked toward the left, moving the pivoted reversingswitch, so that its arms 25 and 26 will respectively connect stationarycontacts 18 and 21. At the same time the generator field circuitcorresponding to the sectionA' will. have become partially energized,the circuit bein from the main 12 through lead 33, to the i ield coils34, through the lead 45 to contact 39, then through the resistances 42and 43 in series to contact 41 through control arm 36, lead 46 and lead16, back to the main 11.

The generator field being now excited and the reversing switch beingconnected as described, current will be supplied from the generatonbrush7 through lead 17 to the stationary contact 18, through the blade 25 andlead 29 through motor armature 13 and from the armature through the lead29 to the blade 26, contact 21 and lead 20 to the generator brush 10.The motor 13 being separately excited from mains 11-12, now operates tocause the elevator car to ascend at slow speed.

Upon further movement of the control arm 36 toward the left theresistances 43 and 42 will be successively cut out of the generatorfield circuit and when the contact 39 is reached by arm 36 the fullvoltage of the mains l1 and 12 will be'applied tothe field of thesection A of the generator, and the elevator car will ascend at fullspeed.

When the controller arm 36 cooperates with contact 39, the resistances42 and 43 are in series with the electro-ma et 47 so that the fullvoltage across the mains Hand 12 is no longer applied to the saidelectro-magnet, a lesser voltage being sufiicient to hold the switchclosed than that needed for efiecting closure. The elevator will ascendas long as the controller arm 36 remains in cooperation with contact 39,the usual limit switch (not shown) being employed to automatically cutoff the current when the car reaches its greatest height.

The speed of the elevator may be regulated for a slower speed by movingthecontroller arm intoengagement with contact 42 and it may be stillfurther'retarded by placing the arm 36 in cooperation with contact 41.When it is desired to stop the elevator, the controller arm 36 isreturned to neutral position. As. .the arm 36. successively cutsresistances 42 and 43 intothe gen-- I I erator field, a gradualdeceleration of the car thus takes place prior to stopping.

When controller arm 36 has reached the contact 41 the full voltage ofthe supply mains 11 and 12 is again applied across the coil 47 thecurrent supplied to the motor from the generator having been reduced bythe insertion of the resistances 42 and 43 in series with thefield-section.

As soon as control arm 36 is moved out" of engagement with contact 41into neutral position the generator field circuit is broken and thevoltage, and magnitude of current supplied to the motor 13 is quicklycut down.

When it is desired to cause the elevator to descend, the control arm ismoved to the right. The action upon the reversing switch in this eventis to 'move said switch so that its blades 25 and'26 respectively are inengagement with the stationary contacts 23 9 and 18. When the switch isin this position, current is at first supplied from the generatorsection to the motor 13 in a direction the reverse of that forlifting'the car, and the motor their acts'to. overcome any resistance 10opposing descent of the car. If, on the other hand, the elevator and itsload have a greater mass than the counterweight, the elevator thereupondescends by gravity, operating the motor 13 as a generator and when themotor is driven at a sufliciently high speed to generate a voltage inexcess of the generator section A, it will deliver current back to saidsection, thus assisting the prime mover by reducing the output requiredfrom the generator. As is obvious from the above description, the returnof the reversing switch from the last-described position will take placewithout objectionable sparking.

As above noted, the description of the operation of elevator motorsystem A will also appl to the system B or to as many additionalelevator motors as may be supplied from a multi-voltage generator withthe appropriate number of poles. In this system each elevator motor isoperated independently of all of the others so that com pleteflexibility of service may be secured. In idle hours less than the fullnumber of elevators, or if desired only a single elevator may be setinto operation, and this, regardless of the number of sections that themultivoltage generator may have.

In my preferred arrangement I employ the reversing switch described toreverse the 0 direction of current in the field coils of the hoist motorbut, particularly with large motors, an appreciable amount of time isrequired to discharge and remagnetize the field, Whereas the action ofthe switch in the n main circuit is practically instantaneous.

In the above described apparatus of Figure 1, any desired source ofpower may be used for driving the armature l at the desired operatinspeed. Such source of power may operate through the shaft on which thearmature is mounted or if desired, may con sist of suitable connectionswhereby one pair of poles and one pair of brushes of the generator areconnected to the line so as to act as a motor for driving said generatorarmature.

One way of thus connecting one pair of poles and brushes for drivingpurposes is indicated in Figure 2. In this figure the coils of the righthand pair of field poles are energized as in Figure 1 through wire 33connected to one side of the power circuit 12, the return to the otherside of the power circuit 11 being throughwire 16. The brushes 8, 9 areconnected to 11 and 12 respectively by wires 17, 20. Thus arranged theright hand pair of field poles and the armature windings between brushes8 and 9 operate as the driving motor while the other pair of poles andrushes 7, 10 are operating in the manner described above in connectionwith Figure 1.

As before stated, there may be any desired number of pairs of poles andbrushes. Any one or more of said pairs may be used for motive powerpurposes and any other one or more of said pairs can be used forgenerator purposes.

Although I have disclosed and described my system specifically forelevator operation, it is to be understood that it is susceptible 01"".a variety of analogous uses, as for instance to the control of electricmine hoist systems. I

As my invention is capable of numerous embodiments without departingfrom the scope thereof, all matter contained in the above description orshown in the accompanying drawings is to be interpreted as illustrative,and not in a limiting sense.

I claim:

1. In an electrical system in'combination, a multi-voltage generatorhaving a plurality of pairs of poles, a plurality of pairs of brushesassociated, one pair with each pole pair, separate load circuits subjectto reversal of power interchange with the gen erator connected eachacross a separate and distinct pair of said brushes, means forcontrolling each said load circuit independently of the others forfrequent and rapid interchange of energy between the circuits.

2. In an electrical elevator system in combination, a multivoltagegenerator, having a plurality of pairs of poles, a plurality of pairs ofbrushes, associated, one pair with each pole pair, a plurality ofelevator motors, connected each across a separate and distinct pair ofsaid brushes, and means whereby the starting, acceleration, stopping andreversal of each of said motors may be independently controlled wherebyenergy regenerated by one of the elevator motors will fiow through thewindings of the generator to supply current to another of said motors.

Signed at New York city in the county of New York and State of hew'Yorkthis 6th day of November, A. D. 1919.

SAMUEL W. RUSHMORE.

